1. Field of the Invention
The present invention relates to methods for selectively forming objects (for example, a film, a wiring, an insulating layer, a mask, or the like) by discharge of droplets. In detail, the present invention relates to film forming devices, film forming methods, droplet discharge devices and droplet discharge methods, which are used in manufacturing components used for semiconductor devices, display devices, and the like.
2. Description of the Related Art
In the droplet discharge method typified by an ink-jet method, a material supplied from a material supply container is discharged (ejected) from an outlet through a pressurizing chamber (also referred to as a pumping chamber). In the pressurizing chamber, pressure is applied using a piezoelectric converting system (such as a piezoelectric element) or a thermal conversion system, thereby discharging the material therefrom.
In some cases, bubbles are in the pressurizing chamber due to mixture of air, or the like when supplying the material to the pressurizing chamber. Since the bubbles are gas, bubbles easily expand and shrink than liquid. Therefore, when bubbles are in the pressurizing chamber, the applied pressure is absorbed by the gas. Consequently, inability to apply sufficient pressure to liquid causes defective discharge. In addition, there is a possibility that even a bubble that is in the material supply container also flows into the pressurizing chamber during discharging and causes defective discharge.
As a method for removing such bubbles in the pressurizing chamber, there is a method in which bubbles in the material in a head portion are exhausted by exhausting the material from an outlet. Such a method has also been proposed in which hydrophilization treatment is performed inside a supply pipe where ink is supplied so that a bubble is removed more easily (for example, see Patent Document 1: Japanese Published Patent Application No. 2001-162817).
However, with the use of the method in which bubbles are removed by exhaust of a material as described above, a large quantity of materials is consumed in vain, which causes great loss in cost. In addition, depending on characteristics of materials, for example, in materials containing surfactants having a high foaming property such as fluorine-based surfactants it is difficult to remove a bubble completely just by exhaust of a large quantity of the materials.